IMC
Instance Method Call

<?php
class foo {
    public $x = 1;
 
    public function getX() {
        return $this->x;
    }
    public function setX($val) {
        $this->x = $val;
        return $this;
    }
}
 
$X = (new foo)->setX(20)->getX();
echo $X; // 20

Combine with Function Array Dereferencing

<?php
class foo2 {
    public $x = [];
 
    public function getX() {
        return $this->x;
    }
    public function setX($arr) {
        $this->x = $arr;
        return $this;
    }
}
 
$X = (new foo2)->setX([0,10,20,30])->getX()[2];
echo $X; // 20

Instance Method Array Dereferencing

<?php
class foo extends ArrayObject {
    public function __construct($arr) {
        parent::__construct($arr);
    }
}
 
echo (new foo( [1, [4, 5], 3] ))[1][0]; // 4